adb

The command-line hinge between your workstation and an Android device or emulator. Learn the small surface of adb itself (device selection, transport, files) and the huge surface of the on-device commands it exposes (pm, am, dumpsys, cmd, settings, input, screenrecord, wm, getprop).

Pair with apktool for patch cycles, frida for runtime hooking, jadx for static review, mobile-technique for triage, and Macrobenchmark for on-device performance work.

Fundamentals

adb devices -l                      # first line every session — solves 80% of "why nothing works"
adb -s <serial> shell               # target a specific device when multiple attached
adb -e shell                        # emulator only
adb -d shell                        # physical device only

adb kill-server && adb start-server # reset when adb behaves erratically
adb reconnect                       # force USB re-enumeration
adb root                            # request root (userdebug/eng only; noop on stock)
adb unroot                          # revert to shell UID